Loader excavator accessories 201-0950 solenoid valve assembly

Electromagnetic proportional valve working principle and detection:

Valve control of flow can be divided into two types:
One is switch control: either fully open or fully closed, the flow rate is either large or small, there is no intermediate state, such as ordinary electromagnetic through valves, electromagnetic reversing valves, electro-hydraulic reversing valves.
The other is continuous control: the valve port can be opened according to the need of any degree of opening, thereby controlling the size of the flow through, such valves have manual control, such as throttle valves, but also electronically controlled, such as proportional valves, servo valves.
So the purpose of using proportional valve or servo valve is: to achieve the flow control by electronic control (of course, after structural changes can also achieve pressure control, etc.), since it is throttling control, there must be energy loss, servo valve and other valves are different, its energy loss is greater, because it needs a certain flow to maintain the work of the pre-stage control oil circuit.

The main valve of the servo valve is generally the same as the reversing valve is a slide valve structure, but the reversing of the valve core is not driven by an electromagnet, but by the hydraulic pressure output of the pre-stage valve, which is more similar to the electro-hydraulic reversing valve, but the pre-stage valve of the electro-hydraulic reversing valve is a solenoid reversing valve, and the pre-stage valve of the servo valve is a nozzle baffle valve or jet pipe valve with better dynamic characteristics.
That is to say, the main valve of the servo valve is controlled by the output pressure of the pre-stage valve, and the pressure of the pre-stage valve comes from the inlet p of the servo valve, if the pressure of the p port is insufficient, the pre-stage valve can not output enough pressure to promote the main spool action.